Some duels or similar combats are meant to end when one of the participants causes the other to bleed or be otherwise injured. Whether or not this actually happens often depends on circumstances, but this is a stated stipulation or assumption of at least one participant.
- First Blood, when a combatant having blood drawn on them indicates that the fight is more serious than first thought.
- Single-Stroke Battle, where a swordfight ends with one participant killed by the other on their first swing.
Contrast Duel to the Death.
- In the 1930 storyline of Baccano!, Firo knife fight with Maiza serves the role of a Gang Initiation Fight, with drawing first blood being the main rule. The other rule is that if you go for the kill, you'll be killed where you stand.
- At one point in Fullmetal Alchemist, Gori attacks Gluttony, declaring that the first to bleed is the first to fall.
- Played with in De cape et de crocs. While on the Moon, Armand is challenged to a local form of dueling called rixme, a portmanteau of rixe (brawl) and rime (rhyme) where the loser is the first to lose his flow. It's essentially an Enlightenment-era rap battle.
Armand: Until first blood?
Adynaton: Until the last word.
- The Many Sons Of Winter: Domeric and Joffrey's duel is fought this way. The former wins by hitting the latter in the head and causing him to bite his tongue.
- Die Another Day: While James Bond and Gustav Graves are fencing at the Blades club, Bond proposes a bet over a diamond marked with the insignia of Graves's company (which also happens to be an African conflict diamond). Graves accepts, then takes a pair of decorative swords off the wall.
Graves: Since we're upping the wager, let's up the weapons, shall we? We'll do this the old-fashioned way, first blood drawn from the torso!
- An interesting exploitation of this trope happens in Rob Roy. At the very start of the film, Rob and company track down and capture a group of men who had stolen a herd of cattle from a Scottish lord, and Rob kills the leader in a duel. Later in the film, Will Guthrie, a friend of the leader of the thieves, comes up to Rob in an inn with his sword drawn, challenging Rob to a duel for revenge. Rob gets Guthrie to agree that the duel be to first blood only, then immediately reaches out, cuts his hand on Guthrie's drawn sword, and "congratulates" the other man on his victory. This handily (no pun intended) satisfies honor and leaves Guthrie no recourse for further revenge while also removing the chances of anyone dying in a duel, either via Rob accidentally killing Guthrie or Guthrie "accidentally" killing Rob by scoring a lethal first wound and then later pretending that he never intended to kill Rob.
- The Duellists:
- Feraud's first onscreen duel against a mayor's nephew is considered over after Feraud stabs the man through the chest, drawing blood and humiliating him, but it's later said that he will survive.
- Averted by Feraud and d'Hubert's subsequent many, many duels, which are often plenty bloody, but are always interrupted before they can finish each other off.
- In Dune, when Paul cuts Jamis during their duel, he asks if Jamis wishes to end the fight. This draws anger and disgust from the other Fremen until Jessica explains that Paul was trained to fight to first blood. He then learns that among the Fremen, such duels are to the death.
- In the Honor Harrington books, duels on Manticore have two protocols, one for "first blood" (although death is still possible) and one for "until one is dead or both are out of ammo".
- Exaggerated in The Man Who Was Thursday, when a duel that's meant as a distraction is stipulated to go to first serious injury to make sure the distraction lasts long enough.
- In the Warhammer 40,000 novel Chapter War, Eumenes challenges Sarpedon in the opening, with Sarpedon insisting on the fight being to first blood. They fight again in the climax, this time to the death.
- Subverted in Reflections of Eterna (Winter Break), when Richard Oakdell challenges Valentine Pridd over a perceived insult and Valentine chooses to duel until first blood, but their respective seconds don't manage to stop the duel before both have wounded each other.
- Some hardcore wrestling leagues have "first blood" matches, where the first wrestler that bleeds loses the match. TNA had a variant called Sadistic Madness, in which a wrestler couldn't be pinned until they had been made to bleed.
- In Legend of the Five Rings, iajutsu duels are a common way for rival bushi in Rokugan to settle differences, with first blood usually being the winning stipulation as the swordsmen's lives are too valuable to waste.
- The Dwarven Provings in Dragon Age: Origins are to first blood. Companion Oghren is banned from Provings or even carrying weapons in Orzammar due to accidentally killing an opponent.
- Solatorobo: On the Duel Ship, Red will occasionally find himself in a Self-Imposed Challenge where he declares that he'll win without taking a single hit, making it a duel to the first blood for his opponent, while Red still has to defeat them the normal way.
- Kill Six Billion Demons: Invoked by the immortal God-Emperor Solomon David, who offers one wish — up to and including his own throne — to anyone who can draw one drop of his blood in a duel. Since he's Nigh Invulnerable Person of Mass Destruction, none of the chancellors vying to become his heir are willing to try.
- Heric from Xcalibur once had to fight in such a duel. Since he was not only a mage apprentice, but also a Bare-Fisted Monk, all it took was a kick in the face.
- In Transformers Aligned Universe, this is why Megatron leads the forces of the Decepticons. He and Soundwave — his information officer — duelled for the leadership of the Decepticons during the faction's inception in a fight that was explicitly first to wound. Megatron himself has admitted that had the duel been to the death, Soundwave would have won, and Transformers: Prime makes it blindingly obvious that anyone thinking of overthrowing Megatron has second thoughts because even if Megatron is out of the way, Soundwave isn't, his loyalty to Megatron is undying as a result of the first-to-wound duel, and due to his role as information officer he likely already knows what they're planning.
- Holmgang duels between real life Norsemen were often done like this when they weren't a duel to the death , especially in Iceland. From Kormák's saga:
Each contestant was to have three shields, and when they were destroyed then he must step on the cloak again if he had left it before, and defend himself with his weapons thereafter. He who had been challenged was to have the first blow. If one of the two was wounded so that blood flowed on the cloak, then no further fighting was to be done.
- The option for this is included in a number of dueling codes, in an attempt to keep the body counts down in societies where dueling is considered acceptable behavior. Of course, in fights with real weapons, it is entirely possible for the first blood to stem from a crippling or fatal injury.
- An increase in duels that use this trope is the reason for the design of the épée, eventually developing a three-pronged point that would gouge out a small chunk of flesh in a painful but rarely dangerous way before making the transition to an electronic scoring system. This is why modern épée fencing has no right-of way rules and works purely on who hits first - unlike foil and sabre, which were derived from training for fights to the death and thus make defending against attacks a higher priority.